The present invention relates generally to vacuum filtration devices, and more particularly to a novel disposable vacuum filtration device for separating solid particulate material from a liquid specimen.
In many types of testing and analysis, it is a common practice to require the filtration of a liquid, after which the material retained by the filter element is available for diagnosis or further testing or analysis with other reagents. Similarly, liquids which may have mico-organisms or antibodies present are frequently analyzed by filtering procedures for incubating and analysis. In addition, liquids such as various types of body fluids may have solid test reactants mixed therewith after which the solid reactants are extracted from the liquid by filtering to facilitate analysis of the reactants.
One technique for filtering liquid reagents is to employ a vacuum filtration device having a filter element on which a liquid sample is placed. The liquid is drawn through the filter by vacuum so that the desired contituents are retained on the filter element. See, for example, U.S. Pat. Nos. 2,005,406, 2,896,787, and 3,782,175 each of which employs a vacuum chamber adapted to support a filter element at its upper end and which is operative to filter a liquid sample through the filter element when the vacuum chamber is connected to a source of vacuum. Another device which utilizes suction to draw the liquid portion of a specimen through a filter element and which facilitates both on-site filtering and incubation of micro-organisms in liquid specimens is disclosed in U.S. Pat. No. 2,879,207.
The filtering devices exemplified by the aforementioned U.S. exhibit a number of drawbacks. For example, they require a separate vacuum source such as a vacuum pump to effect vacuum filtering; they are relatively bulky and cumbersome to use; and they require rather complex manipulation to accomplish the desired vacuum filtration.
Marion Laboratories, assignee of the present application, is the owner of U.S. Pat. Nos. 3,891,331; 4,014,748 and 4,311,792 which disclose the use of frangible glass ampules contained within a flexible tube and used for packaging and dispensing reagents. Also known in the prior art is the use of frangible glass ampules having breakable tips to facilitate the passage of a gas to be tested through reagents within the ampule. However, the use of an evacuated ampule or the use of reagents to create a vacuum within an ampule so as to draw liquid through a filter element is not disclosed in the prior art.